Wattage (W)
The unit for measuring electrical power. It defines the rate of energy consumption by an electrical device when it is in operation. The energy costs of operating a device are calculated as its wattage times the hours of use. In single-phase circuits, it is related to volts and amps by the formula Volts x amps x PF = Watts (for AC circuits PF must be included).
Lumens (Lm)
A unit of light flow, or luminous flux. The lumen rating of a lamp is a measurement of the total light output of the lamp.
Lux (Lx)
A unit of illuminance or light falling onto a surface. One lux is equal to one lumen per square meter. Ten lux approximately equals one foot candle.
Candela (Cd)
Unit of luminous intensity, describing the intensity of a light source in a specific direction.
Color Rendering Index (CRI)
A scale of the effect of a light source on the color appearance of an object compared to its color appearance under a referenced light source. Expressed on a scale of 1-100, where 100 indicates no color shift. A low CRI rating suggests the colors of objects will appear unnatural under that particular light source.
Lumen Maintenance Ratio (LMR)
The proportion of the light output of a lamp after a stated period compared with initial lumen output.
Color Temperature (K-Kelvin)
The color temperature is a specification of the color appearance of a light source, relating the color to a reference source heated to a particular temperature, measured by the thermal unit Kelvin. The measurement can also be described as “warm” or “cool”. Generally, sources below 3000K are considered warm, 3000K-4200K is considered bright and those above 4200K are considered cool sources.
